Bluetooth Low Energy Internet of things

Adel Ben OthmanID : 41067771

● Benefits of BLE .● BLE Goals● BLE applications.● BLE Applications.● Challenges and Solutions.● What changed ?● Low Power consumption.● Compatibility and Dual Mode.● Managing complexity (GATT).● Link Layer states● conclusion

Table of Contents

•As the name of technology implies; BLE offers very low power consumptionOutput Power: ~ 10mW (10dBm)Max Current: ~ 15mA

•Very low cost (compared to the classic BL)•Efficient and robust (Adaptive Frequency Hopping, 24 bit CRC ).•Small size •Better range (GFSK @ 2.4 GHz ) 150 meters open field•Low latency (3 ms )•Unlicensed (ISM)

Benefits of BLE

•Optimize power consumption and make power operation as low as possible •Less time to establish a connection (low latency)•Reduce the complexity •Interoperability

Throughput in BLE doesn't matter !Bluetooth low energy is not meant to be about throughput or optimized to have high data rates, it designed basically to

• send a small portion of data (mostly states information)

•do that with the lowest power consumption (run from coin cells )

•and as fast as possible (less latency)

BLE Goals

- It’s all about transferring small data (stats) with low energy.- A website receives these data from dvice via transparent gateways (pipe).- Collect and analyze data to provide service.

BLE Applications : Basics

Temp : 97 F 250 cal

35 mph

12:35 PM

Humidity : 95% 09:00 AM

BLE Applications : Gateway

BLE Applications

Minimizing Power consumption requires :•Taking advantage of - not connected- states to make devices go to sleep as much as

possible ( RF is off most of the time) •Simplifying the discovery and connection procedure with new Generic Attribute

Profile will reduce the complexity thus reduce the requirement of number of operations and memory size which lead to less power consumption to increase the lifetime of the battery .

• This will decrease the cost of the BLW components ( 80% -60% less compared to the BR bluetooth )

•Offering a “connection- less” MAC for data

Challenges and Solutions

- New protocol stack.- new profile architecture - Physical layer

Splits the 2.4 GHz ISM band into 40 channels •3 Advertising Channels •37 Data Channels •fn= 2402 + 2n MHz

- New advertising mechanism, with discovery & connection procedure- Asynchronous connection-less MAC:- New Generic Attribute Profile to simplify devices and the software

What changed ?

RF in BLE is off most of the time leads to :•Lower standby time (less time in active states ‘lower duty cycle’) :

- BLE technology uses only 3 advertising channels compared to Bluetooth technology that uses 16 to 32 channels- RF is on for 1.2 ms instead of 22.5 ms-Deep sleep current is the dominate

•Faster Connections A device that is advertising is able to connect to a scanning device

•The devices can connect and send an ACK in 3 ms •compared to traditional BL can take up to 100 ms to set link connection

Low Power consumption

Lower Peak Power • Using a relaxed RF parameters•In addition to robustness provided by GFSK modulation, increasing the index of the

modulation up to 0.5 in BLW led to improve the range the range .Packet length restricted • lowest complexity of transmitter and receiver.

GFSK Modulation •Modulation index 0.5 → better range than classic Bluetooth • Fewer advertising channels (3 channels )•Reduces power consumption •Faster connection (low latency (3ms) )

Low Power consumption

- To have compatibility with classic BL- Implemented with low cost

Dual mode

● A new method to profile stats and characteristics.● Data to be read uses attributes ( Type ,Value, handle .. ) ● An attribute is a labeled piece of certain data ● Handle : 16 bit handle -unique on the server● Type : the type of this attribute (Time, temperature .service ..etc)● Value : the data itself temp = 80 F● 0 to 512 octets in length (< 20 octets efficient)

Attributes

• Using a new technique to profile “ Generic Attribute Profile (GATT)” : easy to implement with low cost .

•Using this protocol will guarantee less data exchange between devices which will help to decrease the power consumption.

•As a single device may support many services •Service attribute is grouping the characteristics for a service together.•Data to be read uses attributes .•The type of this attribute is represented by Universal Unique Identifier (UUID)

•Services are identified by a UUID •16 bit Bluetooth UUID and 128 bit UUID for specific primary service could be allocated by anyone

Managing Complexity (GATT)

- Still Master /slave topology as classic Bluetooth.

- Master (phone, PC ) ,slave (sensor , thermostat..)

- Slave should be power sensitive.

- Mastre time sensitive .

- Separate data and advertising channels.

Master/Slave

Link Layer States

➢ BLE is here to stay and no intention to replace classic bluetooth.➢ BLE is designed basically to send only small data very fast with minimum

power requirements for a long time. ➢ BLE applications are keep growing and spreading. ➢ BLE constraint was to use as much as the RF and link layers of the

existing classic bluetooth.➢ Dual mode with very low cost can to be compatible with backward

version of BL.➢ BLE can connect anything to internet.

Conclusion

● Bluetooth SIG. (2010). ” BLUETOOTH SPECIFICATION Version 4.0’’. ● Gupta, N. (2013) " Inside Bluetooth Low Energy ". Artech house.● Heydon, R. Hunn,N . “Bluetooth low energy CSR “. retrieved from :

http://www.csr.com ● Villegas, J . Bluetooth Low Energy Version 4.0 Helping create the “internet of

things”. Retrvied from http://home.eng.iastate.edu . ● Decuir, J . (2010 ). “Bluetooth 4.0 : Low energy” Retreived from :

http://chapters.comsoc.org/vancouver/BTLER3.pdf

References